1. Field of the Invention
This invention relates in general to grommets for vehicle wire harnesses and more specifically to a grommet having an engagement surface feature for reducing the force needed to mount the grommet in a vehicle panel opening.
2. Discussion of Related Art
Various methods have been used to reduce the force required to mount a grommet in the opening of a vehicle panel or bulkhead through which a wire harness is routed. The vehicle panel is typically made of sheet metal. In some instances lubricant has been applied to the surface of the grommet that would contact an edge of the opening when the grommet is forced to a seated position. As might be expected, the lubricant spreads over the rest of the grommet, and can get on an assembler's hands and other parts of the vehicle.
An example of a prior art solution that makes structural changes to the grommet contact surface is illustrated in FIG. 1. A grommet 10 has a tubular section 12 that receives and fits around a wire harness. A tapered section 14 substantially surrounds the tubular section 12 and widens to a flange section 16. A groove 18 separates the flange section 16 from the tapered section 14. The groove 18 is sized to receive the edge of the opening through the panel. The flange section 16 seals against a wet side of the panel, and the tapered section 14 presses against a dry side of the panel. The wet side could, for example, be an engine compartment, and the dry side could be a passenger compartment. To mount the grommet 10, the tapered section 14 has to be pulled through the opening until the edge of the opening is received in the groove 18. To provide a tight fit and seal, an outer surface 20 of the tapered section adjacent the groove 18 must be wider than the opening. The grommet 10 uses circumferential ribs 22 around the tapered section 14 at the location of this outer surface 20. The circumferential ribs 22 are meant to provide more flexibility to this outer surface. However, these ribs 22 can catch on the sheet metal of the panel and make it difficult to know when the grommet 10 is seated properly.
Another solution is disclosed in Japanese Patent Application Document 07-115286, published May 2, 1995. A inclined grommet wall is manufactured with a number of projections to provide a point contact with the hole part of an automotive panel and reduce an abrasion coefficient. The projections increase the material needed to produce the grommet, and like the illustrated prior art described above, can catch on a perimeter of the hole.
In U.S. Pat. No. 6,058,562, spaced linear convex surfaces on a tapered surface of a grommet extend longitudinally along the grommet from a wiring harness holding area to an engagement area for gripping the opening in a vehicle panel. The convex surfaces slide along an edge of the opening and inhibit deformation of the grommet by thickening the tapered surface. This type of grommet would seemingly require more material, increasing the grommet cost, and if lubricant is applied the convex surfaces would not limit spreading of the lubricant.